I liked the song and the animation
It was very well made out and though folks might get confused by it, I understood it entirely. The protagonist of the story looked up to the main character of the video game she was taking part in, trying to stop the fighting until she saw that in reality, her ideal hero was just a grunt controlled by the player, not the ideal hero that she always looked up to. She tries to keep out of the way of the fighting in the last part but she gets targetted regardless by both sides for the way she believed things should go.
The last twist at the end of her escaping the video game world and meeting the player is very much taking a twist on the main character reaching the final boss, in this case, Fetusaur is encountering her own final boss, the player who was controlling her former idol.
The song's message is quite simple to my view, it's telling you that people will always try to tell you what to believe in, regardless of if what you believe in is true or not, just to get their own way. You should keep a open mind, but not let yourself be made into a generic grunt of the world you live in.